In all seriousness, I agree with these other posters. I have a Raspberry Pi as a controller and run both Antminer U2s and a Gridseed Orb (aka Mini or 5 Chip), and needless to say there will be a return on investment, but it will be a year or so. I would recommend Antminer U2 or preferably a Gridseed Orb/Mini/5 Chip, because the Gridseed can do either Scrypt or SHA256 or both types of crypto currencies. Other than that. If you want an expensive, but more power friendly dual miner, then get a DualMiner. The DualMiner does 70kh/s for Scrypt or in dual mode 500Mh/s SHA256 & 40kh/s Scrypt.
You can find the above devices on eBay easily for under $25. If you want to make serious coin, then expect to shell out thousands of dollars or of your local currency to make it big, but remember your ROI will take longer as time goes on.
P.S. - I don't intend to get rich, just want a fun hobby and make some "coin"
No, no there won't be an ROI, especially if you count the pi in. At 6 watts you will even lose money, the U2 will make about 1 cent a day (AT CURRENT DIFFICULTY) and difficulty increases. If you have Free power and difficulty NEVER INCREASES @todays rate you will ROI in 15.59 years. (YOU WILL NOT ROI)You can find the above devices on eBay easily for under $25. If you want to make serious coin, then expect to shell out thousands of dollars or of your local currency to make it big, but remember your ROI will take longer as time goes on.
P.S. - I don't intend to get rich, just want a fun hobby and make some "coin"
Now things are a LOT worse for the dualminer 2.57$ a YEAR at current difficulty with no electric. So lets just say that won't ROI either.